import java.util.function.DoubleToIntFunction;

public class Test {
    public static void main(String[] args) {
        String s1="Hello";
        String ret=s1.toLowerCase();
        System.out.println(ret);
        System.out.println(s1);
        System.out.println("------------------");
        String s2="hello";
        System.out.println(s2.toUpperCase());
        System.out.println(s2);
    }
}
